#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <time.h>

inline int get_rez(int tip, int x, int y) {
	if (tip == 0 && (x || y))
		return 1;

	if (tip == 1 && (x || (!x && !y)))
		return 1;

	if (tip == 2 && (y || (!x && !y)))
		return 1;

	if (tip == 3 && (!x || !y))
		return 1;

	return 0;
}

int main() {
	
	freopen("party.in", "r", stdin);
	freopen("party.out", "w", stdout);

	srand(time(0));

	int n, m, value[110], edge[3][1010];

	scanf("%d %d", &n, &m);
	for (int i = 1; i <= m; i++)
		scanf("%d %d %d", &edge[0][i], &edge[1][i], &edge[2][i]);
	memset(value, 0, sizeof(value));

	int ok = 0;
	while (!ok) {
		ok = 1;
		for (int i = 1; i <= m; i++) {
			int rez = get_rez(edge[2][i], value[edge[0][i]], value[edge[1][i]]);

			if (rez == 0) {
				ok = 0;

				int poz = rand() % 2;
				value[edge[poz][i]] = 1 - value[edge[poz][i]];
			}
		}
	}

	int nrsol = 0;
	for (int i = 1; i <= n; i++)
		nrsol += value[i];

	printf("%d\n", nrsol);
	for (int i = 1; i <= n; i++)
		if (value[i])
			printf("%d\n", i);

	return 0;
}